Stimulation of STN impairs aspects of cognitive control in PD.

OBJECTIVE

To test the hypothesis that subthalamic nucleus (STN) stimulation in Parkinson disease (PD) patients affects working memory and response inhibition performance, particularly under conditions of high demand on cognitive control.

METHODS

To test this hypothesis, spatial working memory (spatial delayed response [SDR]) and response inhibition (Go-No-Go [GNG]) tasks requiring varying levels of cognitive control were administered to patients with PD with previously implanted bilateral STN stimulators (n = 24). Patients did not take PD medications overnight. Data were collected while bilateral stimulators were on and off, counterbalancing the order across subjects.

RESULTS

On the SDR task, STN stimulation decreased patients' working memory performance under a high but not low memory load condition (effect of stimulator condition on high load only and condition x load interaction, p < 0.05). On the GNG task, STN stimulation reduced discriminability on a high but not medium inhibition condition (effect of stimulator condition on high inhibition level only, p = 0.05; condition x inhibition level interaction, p = 0.07).

CONCLUSION

STN stimulation reduces working memory and response inhibition performance under conditions of greater challenge to cognitive control despite significant improvement of motor function.